[time-nuts] Time in a cave

[Jim Lux]

On 5/12/15 4:00 PM, Tucek, Joseph wrote:
> I'm looking for information on non-GPS time sources.
>
> For background, I need to provide PTP to a cluster where we don't have line of sight to the sky, and are unlikely to get roof-rights without a fight.  There are CDMA solutions that would work (e.g. Endrun Technologies), but I was wondering if there were any other options.  I either need an indoor capable PTP, or an indoor capable PPS.  Microsemi claims to have an indoor capable "GNSS" system, but I've yet to find a sales rep to talk about it; if anyone has a link to one who can, I'd love to find out the problems^W^W^W^W talk to them about it.
>

But the entire cluster is interconnected?
Or do you need some sort of wireless distribution.

> For an example of something that almost but doesn't quite work, Beagle Software has a CDMA NTP server, but they do neither PTP nor PPS in the CDMA version.  Similarly, Meinberg will sell a PTP unit that freeruns (if you override the config), but they have no solution to discipline via CDMA.
>
> I'm also curious if anyone has any idea about non-GPS time sync after CDMA gets turned off (can I get time from 4G?).
>

What about an off the shelf Rb that puts out 1pps or NTP or PTP.
SRS (http://www.thinksrs.com/products/fs725.htm) does 1pps
MicroSemi (aka Symmetricom,HP,Datum, etc.) has all manner of equipment 
that has quartz or Rb references and probably any interface you care to 
name (for a price).

If you need sync to outside sources periodically, most of these could be 
"carried" to somewhere you have sky visibility to get a GPS 1pps, wait 
long enough to synchronize it up, then carry it back down and go on 
holdover.



> My endgame worst case is to just do PPS from a stratum 2 NTP (or even a freerunning oscillator) and lie to my PTP server; hard sync to UTC is a secondary concern so long as the cluster agrees with itself.  Endrun is looking pretty good, but I'd really like to have a second option to compare against.
>
> -Joe
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>